1. Field of the Invention
The invention relates to the field of radiation physics. More specifically, the invention relates to the field of infrared radiation. More particularly, the invention relates to the guidance of a missile in the presence of background radiation. In still greater particularity, the invention uses dichroic mirrors in a missile seeker system to balance interfering background or countermeasure radiation so as to produce no net missile guidance.
2. Description of the Prior Art
The reliability and effectiveness of optical seeker systems in missiles is affected by outside infrared radiation sources such as sunlit backgrounds or countermeasure flares. Various methods and devices for alleviating this problem have been attempted. One approach has been to cancel signals from sunlit backgrounds and countermeasure flares by making the modulation efficiency of a reticle dependent upon the spectral nature of the source.
One system for spectral discrimination in seeker systems used spectral band pass filters as alternate spokes of a reticle. Spectral filters, however, only allow reflection of predetermined wavelengths of optical energy to achieve background suppression and spectral balancing. In addition, the fabrication of a reticle utilizing this concept is extremely difficult.
Spectral discrimination remains a viable concept however and a seeker system utilizing it would give greater accuracy to the seeker system.